Marvelous reply @Amit Mohanty , +50 upvotes!

Here I am sharing my version!
Sharing you the code for iTextSharp which is used to convert from HTML to PDF.

using System.IO;
using iTextSharp.text;
using iTextSharp.text.pdf;
using iTextSharp.tool.xml;

public void ConvertHtmlToPdf(string htmlFilePath, string pdfFilePath)
{
    using (var fs = new FileStream(pdfFilePath, FileMode.Create, FileAccess.Write, FileShare.None))
    {
        using (var document = new Document())
        {
            var writer = PdfWriter.GetInstance(document, fs);
            document.Open();

            using (var reader = new StreamReader(htmlFilePath))
            {
                var html = reader.ReadToEnd();
                using (var stringReader = new StringReader(html))
                {
                    XMLWorkerHelper.GetInstance().ParseXHtml(writer, document, stringReader);
                }
            }
        }
    }
}

This code reads the contents of an HTML file and writes it to a PDF file using iTextSharp's XMLWorkerHelper class. Some content from the HTML file may be missing in the resulting PDF file, depending on the complexity of the HTML and the capabilities of the PDF conversion library.

To convert an HTML string to a PDF file, you can use a third-party library like iTextSharp, IronPDF, or Select.Pdf.
Here is an example using iTextSharp:

using iTextSharp.text;
using iTextSharp.text.pdf;
using iTextSharp.tool.xml;


Document document = new Document();
PdfWriter writer = PdfWriter.GetInstance(document, new FileStream("output.pdf", FileMode.Create));
document.Open();
string html = "
Hello, world!
";
MemoryStream stream = new MemoryStream(Encoding.UTF8.GetBytes(html));
XMLWorkerHelper.GetInstance().ParseXHtml(writer, document, stream);
document.Close();

Here is an example using Select.Pdf:

using SelectPdf;


PdfDocument document = new PdfDocument();
HtmlToPdf converter = new HtmlToPdf();
converter.Options.PdfPageSize = PdfPageSize.A4;
converter.Options.PdfPageOrientation = PdfPageOrientation.Portrait;
converter.Options.MarginTop = 10;
converter.Options.MarginBottom = 10;

// convert the HTML page to PDF
PdfDocument doc = converter.ConvertUrl("http://example.com");
doc.Save("output.pdf");
doc.Close();

Here is an example using IronPDF:

using IronPdf;
using IronPdf.Rendering;

var Renderer = new HtmlToPdf();
Renderer.PrintOptions.Header = new HtmlHeaderFooter()
{
    Height = 30,
    HtmlFragment = "
Header content
"
};
Renderer.PrintOptions.Footer = new HtmlHeaderFooter()
{
    Height = 30,
    HtmlFragment = "
Footer content
"
};
Renderer.PrintOptions.PaperSize = PaperSize.A4;
Renderer.PrintOptions.MarginTop = 20;
Renderer.PrintOptions.MarginBottom = 20;
Renderer.PrintOptions.MarginLeft = 20;
Renderer.PrintOptions.MarginRight = 20;
var PDF = Renderer.RenderUrlAsPdf("https://www.example.com/");
PDF.SaveAs("output.pdf");

You can pass the URL into the DocumentConverter and convert the HTML to PDF. This should include the missing contents. Here is some sample code which demonstrates this.

using (DocumentConverter documentConverter = new DocumentConverter())         
{         
   var input = DocumentFactory.LoadFromUri(new Uri("HTML file URL"), new LoadDocumentOptions()); // load HTML    
   var output = @"C:\Output\output.pdf");         
   var jobData = DocumentConverterJobs.CreateJobData(input, output, DocumentFormat.Pdf);         
   jobData.JobName = "save to pdf";         
        
   var documentWriter = new DocumentWriter();         
   documentConverter.SetDocumentWriterInstance(documentWriter);         
        
   var renderingEngine = new AnnWinFormsRenderingEngine();         
   documentConverter.SetAnnRenderingEngineInstance(renderingEngine);         
        
   var job = documentConverter.Jobs.CreateJob(jobData);         
   documentConverter.Jobs.RunJob(job);         
}    

https://www.leadtools.com/help/sdk/tutorials/dotnet-convert-files-with-the-document-converter.html